Bearing solutions for main rotor shafts: Asymmetric spherical roller bearings for increased axial load carrying capacity

2015-11-17 | 000-006-437 DE-EN

SCHAEFFLER AG, PARIS/SCHWEINFURT

Schaeffler at EWEA 2015 in Hall P02-3

Bearing solutions for main rotor shafts: Asymmetric spherical roller bearings for increased axial load carrying capacity

FAG spherical roller bearings are suitable for extremely high loads and can compensate for alignment errors and shaft deflections. Schaeffler has consistently developed this proven bearing solution for main rotor shaft bearing supports according to customer requirements in order to increase robustness and service life even further. Along with an optimized internal geometry, the axial load carrying capacity has also been significantly increased thanks to an asymmetric bearing design. The asymmetric spherical roller bearing has a larger contact angle on the bearing row subject to axial loads and a smaller contact angle on the bearing row subject primarily to radial loads. The asymmetric contact angles reduce sliding movements in the drive train through even higher axial rigidity of the bearing. Triondur C, a lamellar, amorphous hydrocarbon coating, additionally provides the bearings with reduced friction and high wear protection under mixed friction conditions.

Optimized internal geometry for greater robustness

The rolling bearings for the bearing support of the rotor shaft are subject to highly-dynamic loads and operating conditions, because all the forces created by the wind affect them directly. Schaeffler develops solutions for all versions of modern wind turbines, from 220 kW to the multi-megawatt class.

Both the conventional FAG spherical roller bearings and the asymmetric roller bearings are characterized by an adjusted internal clearance, close osculation, contoured rolling elements, and a fixed central rib. In FAG spherical roller bearings, the optimized internal geometry provides an overall reduction of contact pressure and wear characteristics, increasing the robustness of the bearing.

It is possible to use an inner ring adjusted to suit the shaft. This simplifies the professional bearing replacement and helps to reduce costs. This way, the rotor shaft can be reused after an overhaul. An additional material application is not necessary.

Protection against white etching cracks with Durotect B

The Durotect B layer system, used in the conventional bearing type, reduces the risk of slippage damage, improves the running-in behavior, and offers protection against corrosion and white etching cracks (WEC). As the result of a consistent development of conventional black oxide coatings, Durotect B has an increased performance potential. Thus, WEC occurred in fewer than 100 bearings of the 550,000 through-hardened bearings coated with Durotect B which were produced and delivered by Schaeffler in the last ten years for use in wind turbines. That corresponds to a failure rate of less than 0.02%.

Greater Reliability with the Schaeffler Wind Power Standard

For the INA and FAG brand wind power bearings, Schaeffler has introduced a wind power standard (WPOS), which makes allowances for the increasing reliability requirements for wind power systems and components. This new standard for products and processes means Schaeffler is ensuring outstanding quality and reliability in wind power and is offering the same high standards of quality as it is already successfully offering in the automotive, aviation, and aerospace industries. The appropriate products will be labeled with WPOS.

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